Method of producing covered wire



July 27, 1937. H. G. SPECHT 2,088;446

METHOD OF PRODUCING COVERED WIRE Fi led Aug. 29, 1934 INVENTOR HHRRY B.EIFEEHT;

ATTORNEY.

Patented July 27, 1937 UNITED STATES PATENT OFFICE METHOD OF PRODUCINGCOVERED WIRE Application August 29, 1934, Serial No. 742,017

1 Claim.

The present invention relates to an improvement in covered wire andmethod of producing the same, an object being to produce a wirecomprising a core of metal or other material 6 and a covering of adifferent material than the core, in a manner whereby the desiredcharac- "teristics of the covering material may be provided withoutrespect to the characteristics of thecore, as distinguished fromprevious methods of 10 producing covered wire wherein the limitations ofthe materials of the core and covering had to be considered andcompromised for, with the result that it was not always possible toobtain all of the desired characteristics in the core and covering. Thiswas particularly true of small diameter covered wire such as silversolder covered wire, and other alloy coatings on hard and soft cores, asused in the formation of soldered seams in wire mesh fabric, and in thejewelry and other trades.

In making solder covered wires or in coating a core of one material withthe shell of another material the methods heretofore employed consistedin rolling and drawing out a billet which had the covering materialbonded about the core. One well-known process consists in turning up acore of material from one inch to six inches in diameter, placing thisin a graphite or other suitable mold, and pouring the melted .30covering material about the core and allowing it to solidify, bindingthe covering material to the core. The billet of combined metal is thentaken from the mold and through a rolling, annealing and drawing processis reduced to the desired wire size. Another method consists inshrinking around a core a shell or tube of suitable bonding material, asfor instance hard or soft solder, and then shrinking on top of this ashell or tube of the desired covering material. This three-piece billetis then heated to a temperature where the middle shell of bondingmaterial will melt and form an intimate union between the cone and theoutside shell. billet is then rolled and annealed and drawn into wire ofthe desired diameter. These methods are used both for producing verysmall diameter covered wire, and also in the making of copper and brassclad wire, and lead coated and other types of wires used in cable andelectrical power lines. Obviously this continual rolling, annealing anddrawing process is expensive and complicated, and has the furtherdisadvantage that it does not permit of covering the core with materialsthat have a lower melting temperature than the annealing tem-,

This

perature of the core. This is because due to the rolling and drawingoperations the material hardens and before it can be further processed,it must be annealed. If the melting temperature of the outside shell isbelow the annealing temperature of the core, the material cannot beannealed, and for this reason it has been impracticable to producesolder covered wire in which the solder had a relatively low meltingpoint and in which the proper malleability and 0 ductility weremaintained. It is also not possible to obtain uniformity in the coveredwire produced by these methods, with the result that the covering mayhave thin and thick spots, the core is apt to be out of center, and thewire 15 is not of uniform cross-section.

According to the present invention I propose to first produce a core ofwire of the proper temper and diameter desired in the finished wire, andproduce separately a strand of covering metal or other material in theform of a fiat ribbon-like strip, which when rolled about the core willcover it. The core wire and covering wire are placed in juxtapositionand are first drawn through a die which bends the covering into U-formabout the core, and then through other dies which close the coveringover the core. In the case of a metal covering the seam of the coveringmay be fused, soldered, brazed or otherwise joined to produce a solidcovering, and/or the covering may be bonded at its inner surface to thecore, as by beating to a proper fusing temperature, or by interposing anintermediate bonding layer. By this process I can cover any corematerial with a shell of any covering material, regardless of themelting temperature of either the core or the shell, and the core willalways be perfectly central and of uniform cross-section.

In the accompanying drawing, I have shown diagrammatically by way ofexample an apparatus for carrying out my invention.

Fig 1 is a longitudinal side elevation of an apparatus for producingmetal covered wire, according to my invention.

Figs. 2 to 8 are enlarged sectional views taken along the lines 22 to8-8 of Fig. 1.

Fig. 9 is a fragmentary side view of a modifled form of apparatus inwhich an intermediate layer is interposed between the flat strip and thecore, and the two formed about the core together, according to analternative method of carrying out my invention.

Fig. 10 is an enlarged sectional view taken along the line III-I0 ofFig. 9. 55

Fig. 11 is a fragmentary side view of a further modified form ofapparatus and showing the method of laying in a solder strip, accord ingto an alternative method of carrying out my invention.

Fig. 12 is an enlarged sectional view taken along the line l2-l2 of Fig.11.

Fig. 13 is a fragmentary side elevation of still another form ofapparatus in which two layers are successively formed about the core,according to still another alternative method of carrying out myinvention.

Figs. 14 to 18 are enlarged sectional views taken along the lines "-14to i8-i3 of Fig. 13.

Fig. 19 is a side elevation of an apparatus for producing a covered wireaccording to my invention where the covering consists of other materialthan metal.

Referring to the drawing and particularly to Figs. 1 to 8, the core wireis designated as A and the covering strip, which may be of metal or anysuitable material, is designated as B. This material may either be firstprepared in the form of a fiat ribbon-like strip, or it may be fed intothe machine in the form of a circular crosssection wire between a pairof rolls ill and II which are designed to flatten the wire to producethe ribbon-like strip of the proper dimensions. In this latter case thestrip B will preferably be fed through an annealing unit i2 before beingcombined with the core. The covering material is fed through a feedroller [3 having a groove ll therein into which the material fits, andthe core wire A is fed from a spool l5 beneath a roller 16 having agroove II to receive it and positioned above the roller l3 so that thecore A is centrally imposed upon the covering strip B. From this pointthe core and covering strip are fed through the machine together, beingfirst carried through a die ll, having an opening is therethrough, whichis of a size to bend the covering strip into U-form about the core, asshown in Fig. 5. The wire then passes through a second die 20, having apassage 2| therethrough, and which is designed to partially close thecovering material B about the core, as shown in Fig. 6. It then passesthrough another die 22, having a passage 23 therethrough, which bringsthe edges of the covering material into abutting relation, so that thecore and covering material is now of circular cross-section as shown inFig. '7. In passing through the dies the forming of the covering aboutthe core is progressive and gradual, the die openings merely varying indiameter to accomplish this. The covered wire is drawn through the diesI3, 20 and 22 by means of a suitable capstan 24, and passes from thiscapstan through a sizing and finishing die 25, having an opening 26therein, which is designed to produce the desired diameter of the finishwire, being drawn through this die by means of a capstan 21. Prior topassing through the die 25 the edges of the covering stripB aresubjected to a melting or fusing'operation, so that as it passes throughthe sizing and finishing die the covering material is in the form of acontinuous solid covering about the core. For the purpose ofillustration I have shown a torch 28 directed against the seam at apoint before 7 the covering wire passes through the die 25. It

will be understood that any suitable means for producing the desiredmelting or fusing operation may be employed. Due to the shaping of thecovering, both through its transverse bending aboutthe core and throughits being drawn through the finishing die 25, it is desirable to annealit and for this purpose I have shown an annealing unit 29 between thecapstan 21 and the spooling unit 30.

In Figs. 9 and 10 I have shown an alternative 6 manner of carrying outthe invention by feeding a thin fiat strip of material C from a spool 31between the core A and the covering material B, this strip being of asuitable bonding material as solder which will melt and form an intimatein union between the core and the outside shell, and between the edgesof the covering material. The strips B and C are formed about the corein the same manner as the single strip B and prior to passing throughthe sizing and finishl5 ing die are subjected to a heating operationdesigned to melt the strip C. Instead of feeding in a separate strip Cthe covering strip 13 may be coated at one side with a layer of bondingmaterial.

In Figs. 11 and 12 I have shown an alternative manner of securing theedges of the covering material. A strip of solder D, preferably ofwedge-shape in cross-section, is fed between the edges of the coveringmaterial just as the wire 25 enters the die 22, the solder strip beingfed from a suitable spool 32 beneath a grooved guide roller 33. In thiscase the covering material will be so dimensioned that when it is closedabout the core a space is provided for receiving 30 the solder strip.The solder strip is thereupon melted or fused with the covering materialby suitable means, as for instance the torch 23.

In Figs. 13 to 18 I have shown a further alternative form in which twolayers are successively formed about the core, the intermediate layer Ebeing of a suitable bonding material in the form of a fiat strip, andbeing first formed about the core as shown in Fig. 1. When thus formedthe outside covering layer F, in the form of a flat strip, is formedabout the core covered with the strip E being fed from a spool 34between grooved guide rollers 35 and 33 and through dies 31, 38 and 33corresponding in function to the dies ll, 20 and 22, as shown in Fig. 1,being drawn therethrough by means of a capstan 40. The covering layer Fis reversely formed with respect to the intermediate layer E so that theseams are diametrically opposed. Before being drawn through thefinishing die 23 the covered wire is subjected to a heating operation tomelt the layer E and bond the covering to the core, and for this purposeI may employ an electric melting furnace 4| having a passage throughwhich the wire moves continuously.

In Fig. 19 I have shown an apparatus for carrying out my invention wherematerial otherthan metal is used as a covering, this material beingdesignated as G. In the case of using a paper, fabric, or other similarcovering the same may first be carried through a bath 42 of rosinous orother suitable material which will subsequently cement the covering tothe core A. The covering material is formed about the core in the samemanner as pointed out above, being drawn through the dies I3, 20 and 22by means of a capstan 24. It may be coated with any suitable coating, asfor instance an enamel coating, by passing it-through a bath 43, fromwhich it passes through the sizing and finishing die 25, through whichit is drawn by the capstan 21 before being wound upon the spooling unit3.. The enamel or other coating may if desired be baked or heat treated,in which case I employ a suitable furnace through which the covered wirepasses as it moves between the finishing die 25 and the capstan 21.

The covered wire produced as above outlined may according to myinvention be re-processed by subsequent drawing and annealingoperations, where it is desired to produce an extremely fine coveredwire, as for instance of .002" in diameter. By this method a moreuniform and accurate covered wire can be produced than has beenheretofore possible where the wire was drawn down from a covered billet.

I have illustrated and described preferred and satisfactory forms of myinvention, but it will be obvious that changes may be made therein,within the spirit and scope thereof, as defined in the appended claim.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:-

The process of producing covered wire which consists in simultaneouslyfeeding between feeding rolls a flat covering strip, a fiat strip ofbonding material, and a separate wire core in longitudinaljuxtaposition, the fiat strip of bonding material being in engagementwith said core, then feeding said strips and core through a successionof longitudinally spaced circular forming dies of gradually decreasingdiameter to form the covering strip and bonding strip from fiat totubular form about the core, the edges of the covering and bondingstrips extending longitudinally of the core, and subjecting the coveredwire to a heating operation at a point between the first and last diesto cause said bonding strip to bond the covering strip to the wire core.

HARRY G. SPECHT.

